<template>
  <div class="channel-edit">
    <van-cell :border="false">
      <div slot="title" class="title-text">我的频道</div>
      <van-button 
        class="edit-btn"
        size="mini" 
        round 
        type="danger"
        plain
        @click="isEdit=!isEdit"
      >{{ isEdit ? '完成' : '编辑'}}</van-button>
    </van-cell>
    <van-grid class="my-grid" :gutter="10">
      <van-grid-item
         icon="clear"
         class="grid-item"
         v-for="(channel, index) in myChannels"
         :key="index"
         @click="onMyChannelClick(channel, index)"
       >
       <van-icon 
          v-show="isEdit && !fiexdChannels.includes(channel.id)" 
          slot="icon" 
          name="clear"
        >
       </van-icon>
         <span class="text" 
            :class="{ active: index === activeIndex }" 
            slot="text">{{ channel.name }}
         </span>
      </van-grid-item>
    </van-grid>
    <van-cell :border="false">
      <div slot="title" class="title-text">频道推荐</div>
    </van-cell>
    <van-grid class="recomment-grid" :gutter="10">
      <van-grid-item
          icon="plus"
          class="grid-item" 
          v-for="channel in recommendChannele" 
          :key="channel.id" 
          :text="channel.name"
          @click="onAddChannel(channel)"
      />
    </van-grid>
  </div>
</template>

<script>

import { getAllChannels,addUserChannel,deleteUserChannel } from '@/api/channel.js'
import { mapState } from 'vuex'
import { setItem } from '@/utils/storage.js'
export default {
  name: 'ChannelEdit',
  props: {
       myChannels: {
         type: Array,
         required: true
       },
       activeIndex: {
         type: Number,
         required: true
       }
     },
     data(){
      return{
        allChannels: [] ,// 所有频道
        isEdit:false,
        fiexdChannels: [0] // 不需要编辑、删除的频道
      }
     },
     computed:{
      ...mapState(['user']),
      recommendChannele(){
        return this.allChannels.filter(channel=>{
          return !this.myChannels.find(myChannel =>{
            return myChannel.id===channel.id
          })
        })
      }
     },
     created(){
      this.loadAllChannels()
     },
     methods:{
      async loadAllChannels(){
        try{
          const { data } = await getAllChannels()
          this.allChannels = data.data.channels
        }catch(err){
          this.$toast('数据获取失败')
        }
      },
      // 添加频道
      async onAddChannel (channel) {
        this.myChannels.push(channel)
        // 数据持久化处理
        if(this.user){
          try{
            await addUserChannel({
              id:channel.id, // 频道 ID
              seq:this.myChannels.length // 序号
            })
          }catch(error){
            this.$toast('保存失败，请稍后再试')
          }
        }else{
          // 未登录，把数据存储到本地
          setItem('TOUTIAO_CHANNELS',this.myChannels)
        }
      },
      // 切换频道
      onMyChannelClick (channel, index) {
        if(this.isEdit){
          // 如果是固定频道，则不删除
          if(this.fiexdChannels.includes(channel.id)){
            return
          }
          // 删除频道项
          this.myChannels.splice(index,1)
          // 如果要删除的激活频道之前的频道，则更新激活的频道项
          // 参数1：要删除的元素的开始索引
          // 参数2：要删除的个数，如果不指定，则从参数 1 开始一直删除
          if(index <=this.activeIndex){
             // 让激活频道索引 - 1
            this.$emit('update-active',this.activeIndex - 1,true)
          }
          this.deleteChannel(channel)
        }else {
          // 非编辑状态，指向切换频道
          this.$emit('update-active', index,false)
        }
      },
      async deleteChannel (channel) {
        try{
          if(this.user){
            await deleteUserChannel(channel.id)
          }else{
            setItem('TOUTIAO_CHANNELS',this.myChannels)
          }
        }catch(err){
          this.$toast('操作失败，请稍后重试')
        }
      },
    }
    }
</script>

<style scoped lang="less">
.channel-edit {
  padding: 85px 0;

  .title-text {
    font-size: 32px;
    color: #333;
  }

  .edit-btn {
    width: 104px;
    height: 48px;
    font-size: 26px;
    color: #f85959;
    border: 1px solid #f85959;
  }

  /deep/ .grid-item {
    width: 160px;
    height: 86px;
    .van-grid-item__content {
      white-space: nowrap;
      background-color: #f4f5f6;

      .van-grid-item__text,.text {
        font-size: 22px;
        color: #222;
        margin-top: 4px !important;
      }
      .van-grid-item__icon-wrapper {
        position: unset;
      }
      .active {
        color: red;
      }
    }
  }

  /deep/ .my-grid {
    .grid-item {
      .van-icon-clear {
        position: absolute;
        right: -10px;
        top: -10px;
        font-size: 30px;
        color: #cacaca;
        z-index: 2;
      }
    }
  }

  /deep/ .recomment-grid {
    .grid-item {
      width: 160px;
      height: 86px;
      .van-grid-item__content {
        flex-direction: row;

        .van-icon-plus {
          font-size: 22px;
          line-height: 22px;
          margin-right: 6px;
        }
      }
    }
  }
}
</style>